1. Field of the Invention
The present invention relates, in general, to filters for use in air conditioners and, more particularly, to a filter provided with carbon nanotubes, in which nano-sized metal particles of at least one type of metal are deposited into each carbon nanotube.
2. Description of the Related Art
As is well known to those skilled in the art, human beings, on average, spend at least 80% of their lives indoors. However, room air is contaminated with tobacco smoke, offensive odors, bacteria, or other hazardous materials that adversely affect the human body. Therefore, the demand for purification of room air is increasing, and, accordingly, research into air purification has been increasing.
Typically, an air conditioner or an air cleaner is provided in homes to purify room air. In an air conditioner, a dust collecting filter, which draws in and collects dust present in room air, is essentially mounted therein.
FIG. 1 illustrates a conventional air conditioner 5 equipped with a dust collecting filter 6 and a deodorizing filter 7. As shown in FIG. 1, the air conditioner 5 adsorbs and removes dust, as well as chemical contaminants, for example, NH3, HCl, HF, organic gases, NOx, or SOx.
The conventional deodorizing filter 7 includes activated carbons, carbon fibers, or ion exchange resins, and is chemically formulated to be suitable for use in various desired purposes.
However, adsorption performance of the deodorizing filter 7 is proportional to a surface area of the filter, in which the maximum surface area of commercially available activated carbon, carbon fiber, or ion exchange resin is no more than 103 m2/g.
To ensure that the activated carbons having the maximum surface area of 103 m2/g remove NH3 gas under conditions of a concentration of 10 ppb and a wind velocity of 0.3 m/s, the filter, including the activated carbons, should be 100 mm thick. Alternatively, the carbon fibers or the ion exchange resins are required to have a filter thickness of 150 mm under the same conditions as those of the activated carbons. Accordingly, the air conditioner is disadvantageous in that it occupies a large volume within the home.
The activated carbons remove odors from air by physical adsorption. However, after adsorption of a predetermined amount or more, the activated carbon filter does not adequately perform adsorption, and odors are not removed from the circulated air.
In the conventional air conditioner 5, the dust collecting filter 6 and the deodorizing filter 7 are separately mounted, thus requiring double mounting costs. Also, it is difficult to maintain and handle the filters.
In areas in which the environment is inferior, such as in various organic materials-generating industrial facilities or during the construction of new buildings, offensive odors that are not removed using a simple filter may cause very serious problems. When humans encounter offensive odors or VOCs (Volatile Organic Compounds: aromatic compounds, alcohols, hydrocarbons, organic acids, ketones, aldehydes, etc.), they may suffer from headaches, as well as disorders of the central nervous system.
Further, when the odors are emitted into atmospheric air, an odor component reacts with nitrogen oxide present in the air to produce ozone (O3) by a photo-oxidation process, thus causing air contamination.
Thus, the VOCs are removed by incineration (heat and catalyst), adsorption recovering organic solvents, absorption, condensation, etc. In addition, new processes, such as membrane separation, ultraviolet oxidation, or corona techniques, are used. However, the above-mentioned processes are difficult to apply to an air conditioner for use in homes in view of cost, volume, and management.
Thus, in homes, VOCs are partially removed by use of ventilators and hoods, as well as by techniques of adsorption using activated carbons and absorbing solution. At present, a filter facilitating adsorption has been widely used.
The adsorption filter is used to efficiently remove low concentrations of VOCs, but does not effectively remove high concentrations of VOCs. Thus, such a filter is disadvantageous in that it needs to be frequently replaced with a new filter due to short service life and high handling cost.